The present invention relates to a drive control device for a motor, and specifically relates to a sensorless vector control device that calculates a position angle of a rotor based on a high-frequency current and a high-frequency voltage running through the motor for use as a position angle in a vector control computation. The sensorless motor control device of the present invention may be used, for example, in an electric vehicle (EV) that uses a motor to drive the wheels, as well as a hybrid electric vehicle (HEV) having a motor whose battery is recharged by driving the engine.
In Japanese Patent Application Publication No. JP-A-H11-299299, a harmonic current generated by a harmonic current generator 10 is overlaid on (added to) id of target currents id, iq on two axes of a motor vector control. A motor voltage is detected and a q-axis voltage is calculated from the voltage, and then differentiated. A positional error detector 15 calculates a positional error, after which a position angle of a targeted gap magnetic flux is calculated. In Japanese Patent Application Publication No. JP-A-2007-236015, an induced voltage of a motor is calculated based on a d-axis voltage command of a motor vector control, and d-axis and q-axis currents of the motor. A position computation then calculates a position angle θ based on the induced voltage.